The readings for the fourteenth Sunday after Pentecost are taken from Ezekiel 34:11-24; 1 Timothy 1:5-17, and Luke 15:1-10.
Ezekiel reports how God Himself will seek out His sheep and bring them back to Himself. God will also judge between sheep.
Paul warned about those who stray, like lost sheep or goats. Paul explained to Timothy that the law is given for the lawless. All of us are goats and lawless because of the corruption of Adam in us. God forgives and atones. God makes us His own sheep when His Word and Spirit regenerate our souls. God redeemed Paul to show His longsuffering. Christ Jesus came into the world to save sinners.
Luke records how tax collectors and sinners drew near to hear—this is what sheep do (read all of John 10!). The Pharisees and scribes came grumbling, pushing and butting against the Good Shepherd. Jesus seeks out the lost until He finds them. The Good Shepherd left the ninety-nine sheep because they were so lost in their own self-righteousness that they could not be found (see Luke 18:9-14 where Jesus makes this contrast clear).